A Troubling Policy

I've been banned from advertising a couple of my books from the Amazon site, and in one case, they are quite literally judging a book by its cover. They are not allowing on-site advertising from books "that contain mature or erotic content." Which applies, certainly, to "Double Blind," which is unabashedly erotic (although also literary). But they've also disallowed it for my road novel, "Exit Wonderland," seemingly based on its saucy cover. How far do we go with this? And does this apply to advertising for "50 Shades of Grey"? "Tropic of Cancer"? "Lady Chatterley's Lover"?